Polymer having polycyclic groups and coating compositions thereof

ABSTRACT

A polymer and coating composition containing the polymer are provided that are useful in coating applications such as, for example, food or beverage packaging containers. The polymer preferably includes a backbone having one or more polycyclic groups. In one embodiment, the polymer is a polyester and, more preferably, a polyester-urethane polymer. In one embodiment, the one or more polycyclic groups is a tricyclic or higher group.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation-in-part of U.S. applicationSer. No. 12/786,089 filed May 24, 2010 and entitled “POLYMER HAVINGPOLYCYCLIC GROUPS AND COATING COMPOSITIONS THEREOF,” which is acontinuation-in-part of International Application Serial No.PCT/US2010/030584 filed Apr. 9, 2010 and entitled “POLYMER HAVINGUNSATURATED CYCLOALIPHATIC FUNCTIONALITY AND COATING COMPOSITIONS FORMEDTHEREFROM,” which claims priority to U.S. Provisional Patent ApplicationSer. No. 61/168,138 filed on Apr. 9, 2009 and entitled “POLYESTERPOLYMER HAVING UNSATURATED CYCLOALIPHATIC FUNCTIONALITY AND COATINGCOMPOSITIONS FORMED THEREFROM.” The aforementioned U.S. application Ser.No. 12/786,089 is also a continuation-in-part of InternationalApplication Serial No. PCT/US2009/065848 filed Nov. 25, 2009 andentitled “POLYESTER POLYMER AND COATING COMPOSITIONS THEREOF,” whichclaims priority to U.S. Provisional Application No. 61/118,224 filedNov. 26, 2008 and entitled “POLYESTER POLYMER AND COATING COMPOSITIONSTHEREOF.” Each of the aforementioned patent applications is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

This invention relates to a polymer and coating compositions formulatedfrom the polymer.

BACKGROUND

The application of coatings to metals to retard or inhibit corrosion iswell established. This is particularly true in the area of packagingcontainers such as metal food and beverage cans. Coatings are typicallyapplied to the interior of such containers to prevent the contents fromcontacting the metal of the container. Contact between the metal and thepackaged product can lead to corrosion of the metal container, which cancontaminate the packaged product. This is particularly true when thecontents of the container are chemically aggressive in nature.Protective coatings are also applied to the interior of food andbeverage containers to prevent corrosion in the headspace of thecontainer between the fill line of the food product and the containerlid.

Packaging coatings should preferably be capable of high-speedapplication to the substrate and provide the necessary properties whenhardened to perform in this demanding end use. For example, the coatingshould be safe for food contact, not adversely affect the taste of thepackaged food or beverage product, have excellent adhesion to thesubstrate, resist staining and other coating defects such as “popping,”“blushing” and/or “blistering,” and resist degradation over long periodsof time, even when exposed to harsh environments. In addition, thecoating should generally be capable of maintaining suitable filmintegrity during container fabrication and be capable of withstandingthe processing conditions that the container may be subjected to duringproduct packaging.

Various coatings have been used as interior protective can coatings,including epoxy-based coatings and polyvinyl-chloride-based coatings.Each of these coating types, however, has potential shortcomings. Forexample, the recycling of materials containing polyvinyl chloride orrelated halide-containing vinyl polymers can be problematic. There isalso a desire by some to reduce or eliminate certain epoxy compoundscommonly used to formulate food-contact epoxy coatings.

To address the aforementioned shortcomings, the packaging coatingsindustry has sought coatings based on alternative binder systems such aspolyester resin systems. It has been problematic, however, to formulatepolyester-based coatings that exhibit the required balance of coatingcharacteristics (e.g., flexibility, adhesion, corrosion resistance,stability, resistance to crazing, etc.). For example, there hastypically been a tradeoff between corrosion resistance and fabricationproperties for such coatings. Polyester-based coatings suitable for foodcontact that have exhibited both good fabrication properties and anabsence of crazing have tended to be too soft and exhibit unsuitablecorrosion resistance. Conversely, polyester-based coatings suitable forfood contact that have exhibited good corrosion resistance havetypically exhibited poor flexibility and unsuitable crazing whenfabricated.

What is needed in the marketplace is an improved binder system for usein coatings such as, for example, packaging coatings.

SUMMARY

The present invention provides a polymer having one or more organicpolycyclic groups. The polycyclic groups may be saturated, unsaturated,aromatic, or a combination thereof, and may include one or moreheteroatoms (e.g., oxygen, nitrogen, silicon, phosphorus, sulfur, etc.)in a ring thereof. The polymer may include any suitable combination ofpolycyclic groups selected from bicyclic groups, at least tricyclicgroups, or polycyclic groups having four or more rings. In oneembodiment, the one or more polycyclic groups are selected fromsaturated, unsaturated, or aromatic bicyclic groups; saturated,unsaturated, and/or aromatic at least tricyclic polycyclic groups; or acombination thereof. Substituted or unsubstituted tricyclodecane,nobornene, and isosorbide groups are examples of preferred polycyclicgroups. In preferred embodiments, the polymer includes a backbone havingone or more heteroatoms, more preferably a backbone including esterand/or urethane linkages. Step-growth polymers such as, for example,polyester polymers, polyurethane polymers, and polyester-urethanepolymers are presently preferred.

In one embodiment, the invention provides a polymer (more preferably apolyester polymer, polyurethane polymer, or polyester-urethane polymer)that includes both unsaturated bicyclic groups and at least tricyclicgroups. A preferred example of such a polymer is a polyester-urethanepolymer that includes a plurality of unsaturated bicyclic groups (morepreferably substituted or unsubstituted norbornene groups) and aplurality of tricyclic groups (more preferably substituted orunsubstituted tricyclodecane groups).

In one embodiment, the invention provides a method for making apolyurethane polymer, more preferably a polyester-urethane polymer, thatincludes reacting ingredients including a polyol (more preferably apolyester polyol) and a polyisocyanate to form a polyurethane polymerhaving one or more polycyclic groups. Preferably at least one of thepolyol or polyisocyanate includes a polycyclic group.

In one embodiment, the invention provides a coating composition thatincludes a polymer, more preferably a polyester and/or polyurethanepolymer, having one or more polycyclic groups. The coating compositionmay optionally include additional ingredients such as a liquid carrier,a crosslinker, and any additional desired additives. In presentlypreferred embodiments, the coating composition is a water-based or asolvent-based coating composition.

In one embodiment, the invention provides articles having a coatingcomposition of the invention applied on at least a portion of a surfacethereof. The coating composition of the invention may have utility in awide range of coating applications including, for example, as apackaging coating, and especially as a packaging coating for use on foodor beverage containers (e.g., metal food or beverage cans), or a portionthereof.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The description that follows more particularly exemplifiesillustrative embodiments. In several places throughout the application,guidance is provided through lists of examples, which examples can beused in various combinations. In each instance, the recited list servesonly as a representative group and should not be interpreted as anexclusive list.

The details of one or more embodiments of the invention are set forth inthe description below. Other features, objects, and advantages of theinvention will be apparent from the description and from the claims.

Selected Definitions

Unless otherwise specified, the following terms as used herein have themeanings provided below.

As used herein, the term “organic group” means a substituted orunsubstituted hydrocarbon group (with optional elements other thancarbon and hydrogen, such as oxygen, nitrogen, sulfur, and silicon) thatis classified as an aliphatic group, a cyclic group, or combination ofaliphatic and cyclic groups (e.g., alkaryl and aralkyl groups).

Substitution is anticipated on the organic groups of the compounds ofthe present invention. As a means of simplifying the discussion andrecitation of certain terminology used throughout this application, theterms “group” and “moiety” are used to differentiate between chemicalspecies that allow for substitution or that may be substituted and thosethat do not allow or may not be so substituted. Thus, when the term“group” is used to describe a chemical substituent, the describedchemical material includes the unsubstituted group and that group withO, N, Si, or S atoms, for example, in the chain (as in an alkoxy group)as well as carbonyl groups or other conventional substitution. Where theterm “moiety” is used to describe a chemical compound or substituent,only an unsubstituted chemical material is intended to be included. Forexample, the phrase “alkyl group” is intended to include not only pureopen chain saturated hydrocarbon alkyl substituents, such as methyl,ethyl, propyl, t-butyl, and the like, but also alkyl substituentsbearing further substituents known in the art, such as hydroxy, alkoxy,alkylsulfonyl, halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus,“alkyl group” includes ether groups, haloalkyls, nitroalkyls,carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On the other hand, thephrase “alkyl moiety” is limited to the inclusion of only pure openchain saturated hydrocarbon alkyl substituents, such as methyl, ethyl,propyl, t-butyl, and the like. As used herein, the term “group” isintended to be a recitation of both the particular moiety, as well as arecitation of the broader class of substituted and unsubstitutedstructures that includes the moiety.

The term “cyclic group” means a closed ring organic group that isclassified as an alicyclic group or an aromatic group, both of which caninclude heteroatoms.

The term “alicyclic group” means a cyclic organic group havingproperties resembling those of aliphatic groups.

The term “polycyclic” when used in the context of a group refers to anorganic group that includes at least two cyclic groups in which one ormore atoms (and more typically two or more atoms) are present in therings of both of the at least two cyclic groups. Thus, for example, agroup that consists of two cyclohexane groups connected by a singlemethlylene group is not a polycyclic group.

The term “tricyclic” group refers to a polycyclic group that includesthree cyclic groups in which the ring of each cyclic group shares one ormore atoms with one or both of the rings of the other cyclic groups.

A group that may be the same or different is referred to as being“independently” something.

The terms “unsaturation” or “unsaturated” when used in the context of acompound or group refers to a compound or group that includes at leastone non-aromatic (i.e., aliphatic) carbon-carbon double or triple bond.

The term “aliphatic” when used in the context of a carbon-carbon doublebond includes both linear aliphatic carbon-carbon double bonds andcycloaliphatic carbon-carbon double bonds, but excludes carbon-carbondouble bonds of aromatic rings.

The term “substantially free” of a particular mobile compound means thatthe recited polymer and/or composition contains less than 100 parts permillion (ppm) of the recited mobile compound. The term “essentiallyfree” of a particular mobile compound means that the recited polymerand/or composition contains less than 5 ppm of the recited mobilecompound. The term “completely free” of a particular mobile compoundmeans that the recited polymer and/or composition contains less than 20parts per billion (ppb) of the recited mobile compound.

The term “mobile” means that the compound can be extracted from thecured coating when a coating (typically ˜1 mg/square centimeter (6.5mg/square inch) thick) is exposed to a test medium for some defined setof conditions, depending on the end use. An example of these testingconditions is exposure of the cured coating to HPLC-grade acetonitrilefor 24 hours at 25° C. If the aforementioned phrases are used withoutthe term “mobile” (e.g., “substantially free of BPA”) then the recitedpolymer and/or composition contains less than the aforementioned amountof the compound whether the compound is mobile in the coating or boundto a constituent of the coating.

The term “food-contact surface” refers to the substrate surface of acontainer that is in contact with, or intended for contact with, a foodor beverage product.

The term “crosslinker” refers to a molecule capable of forming acovalent linkage between polymers or between two different regions ofthe same polymer.

The term “on,” when used in the context of a coating applied on asurface or substrate, includes both coatings applied directly orindirectly to the surface or substrate. Thus, for example, a coatingapplied to a primer layer overlying a substrate constitutes a coatingapplied on the substrate.

Unless otherwise indicated, the term “polymer” includes bothhomopolymers and copolymers (i.e., polymers of two or more differentmonomers or repeat units). Similarly, unless otherwise indicated, theuse of a term designating a polymer class such as, for example,“polyester” is intended to include both homopolymers and copolymers(e.g., polyester-urethane polymers).

The terms “comprises” and variations thereof do not have a limitingmeaning where these terms appear in the description and claims.

The terms “preferred” and “preferably” refer to embodiments of theinvention that may afford certain benefits, under certain circumstances.However, other embodiments may also be preferred, under the same orother circumstances. Furthermore, the recitation of one or morepreferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the invention.

As used herein, “a,” “an,” “the,” “at least one,” and “one or more” areused interchangeably. Thus, for example, a coating composition thatcomprises “a” polyester can be interpreted to mean that the coatingcomposition includes “one or more” polyesters.

Also herein, the recitations of numerical ranges by endpoints includeall numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, 5, etc.). Furthermore, disclosure of a range includesdisclosure of all subranges included within the broader range (e.g., 1to 5 discloses 1 to 4, 1.5 to 4.5, 1 to 2, etc.).

DETAILED DESCRIPTION

In one aspect, the invention provides a polymer having one or morepolycyclic groups. The polymer preferably includes a polymer backbonehaving one or more heteroatoms (e.g., oxygen, nitrogen, silicon, sulfur,phosphorus, etc.) and, more preferably, is a step-growth polymer.Preferred step-growth polymers include polyester polymers, polyurethanepolymers, and copolymers thereof. In certain preferred embodiments, thepolymer has a backbone that includes both ester and urethane linkages.

The polymer preferably includes at least one polycyclic group, and morepreferably a plurality of polycyclic groups (e.g., ≧2, ≧3, ≧4, ≧5, ≧10,etc.). The polycyclic group(s) may be present in a backbone of thepolymer, a pendant group of the polymer, or a combination thereof. Inpreferred embodiments, the polymer includes at least one, and morepreferably a plurality, of backbone polycyclic groups. While notintending to be bound by theory, it is believed that the presence ofpolycyclic groups can result in a binder polymer having properties thatapproach that of conventional BPA-based epoxy resins. It is believedthat the inclusion of polycyclic groups contributes to the polymer ofthe invention having a desirable combination of coating properties suchas, for example, excellent hardness, rigidity, and thermal stability.

One useful measure for assessing the number of polycyclic groups in thepolymer is the weight percent (wt-%) of the polycyclic groups relativeto the total weight of the polymer. In certain preferred embodiments,polycyclic groups constitute at least about 10, more preferably at leastabout 20, even more preferably at least about 30 wt-% of the polymer.While the upper end is not especially limited, in some embodiments, thepolycyclic groups constitute less than about 80, less than about 60, orless than about 40 wt-% of the polymer.

Caution should be exercised when interpreting the wt-% of polycyclicgroups because direct measurement of the weight of the polycyclic groupsmay not be feasible. Accordingly, the aforementioned wt-%'s correspondto the total weight of (a) polycyclic-containing monomers relative to(b) the total weight of the polymer. Thus, for example, if an oligomerhaving a polycyclic group is incorporated into the backbone of thepolymer, the wt-% of polycyclic groups in the polymer is calculatedusing the weight of the monomer that includes the polycyclic group(s)(as opposed to the weight of the oligomer that includes the monomer).Similarly, if the polymer is formed and then a monomer of the preformedpolymer is modified to include a polycyclic group, then the wt-% ofpolycyclic groups in the polymer is calculated using the weight of themodified monomer, which may be based on a theoretical calculation ifnecessary. For example, in some embodiments, bicyclic groups areincorporated into the polymer of the invention via a Diels-Alderreaction of cyclopentadiene across the double bond of an unsaturatedmonomer (e.g., maleic anhydride) present in the backbone of the polymer.In this situation, the wt-% of polycyclic groups in the polymer isdetermined using the weight of the resulting bicyclic-modified monomerpresent in the polymer.

The polycyclic groups can be of any suitable structure. The polycyclicgroups can include one or more heteroatoms (e.g., nitrogen, oxygen,silicon, sulfur, phosphorus, etc.) in a ring of the polycyclic group.Moreover, the polycyclic groups can include one or more double or triplebonds (including, e.g., carbon-carbon double or triple bonds) orcombinations thereof. The double or triple bonds may be included betweenatoms of a ring of the polycyclic group, in a substituent group of aring of the polycyclic group, or a combination thereof. In certainpreferred embodiments, the polycyclic group is an unsaturated group thatincludes one or more carbon-carbon double bonds and, more preferably,one or more carbon-carbon double bonds located between carbon atoms ofone or more rings thereof. In other preferred embodiments, some or allof the rings of the polycyclic group are saturated. Although notpresently preferred, it is also contemplated that one or more, and insome embodiments all, of the cyclic groups of the polycyclic group maybe aromatic.

The polycyclic groups can include any suitable number of ring groups.Examples of suitable polycyclic groups include bicyclic groups,tricyclic groups, and polycyclic groups including four or more ringgroups. Such polycyclic groups may be present in the polymer of thepresent invention in any suitable combination. The polycyclic groups maybe spiro ring systems (i.e., where two rings join at a single commonatom), fused ring systems (i.e., where two rings share two or morecommon atoms), bridged ring systems (i.e., where two rings share threeor more common atoms), or a combination thereof. Fused and/or bridgedpolycyclic groups are presently preferred.

The polycyclic groups can include any combination of suitably sized ringgroups. For example, the polycyclic groups may include any combinationof organic cyclic groups having 3-atom rings, 4-atom rings, 5-atomrings, 6-atom rings, 7-atom rings, or 8-atom or higher rings. Typically,carbon atoms constitute a majority of the atoms making up the rings orall of the atoms making up the rings. In certain preferred embodiments,the polycyclic groups include two or more 5-atom rings, two or more6-atom rings, or at least one 5-atom ring and at least one 6-atom ring.

In some embodiments, the polymer of the invention includes two or moredifferent types of polycyclic groups (e.g., one or more bicyclicgroup(s) and one or more at least tricyclic group(s)). A preferredcombination is one or more unsaturated bicyclic groups (more preferablyone or more substituted or unsubstituted norbornene groups) and one ormore at least tricyclic groups (more preferably one or more substitutedor unsubstituted tricyclodecane groups). In other embodiments, all ofthe polycyclic groups included in the polymer are a same or similar typeof polycyclic group.

Some non-limiting examples of suitable polycyclic groups are providedbelow. It is contemplated that any of the polycyclic groups disclosedherein may be suitably included in the polymer of the present inventionin any combination.

The above polycyclic groups are each represented as a divalent unit ofthe polymer (e.g., a divalent backbone unit) where each “Y”independently denotes another portion of the polymer that can beattached to any suitable atom of the polycyclic group (with theexception of the depicted isosorbide group) and where one Y may be anend group. It is also contemplated that variants of any of the abovedepicted polycyclic structures may be used such as, for example,substituted variants thereof or unsaturated variants thereof. An exampleof an unsaturated variant of a norbornane group is a norbornene group,which is preferred in certain embodiments. Additional examples ofsuitable polycyclic groups for use in the polymer of the presentinvention are provided in PCT Application No. PCT/US2010/0030584 filedon Apr. 9, 2010 and entitled “Polymer Having Unsaturated CycloaliphaticFunctionality and Coating Compositions Formed Therefrom” and PCTApplication No. PCT/US2010/0030576 filed on Apr. 9, 2010 and entitled“Polyester Coating Composition.”

The one or more polycyclic groups can be incorporated into the polymerof the invention using any suitable method. Typically, polycyclic groupsare incorporated into the polymer using a reactant (e.g., a monomer,oligomer, or polymer reactant) having both: (i) one or more polycyclicgroups and (ii) one or more active hydrogen groups such as, for example,carboxylic acid or anhydride groups or hydroxyl groups. Other suitableactive hydrogen groups may include groups having a hydrogen attached toan oxygen (O), sulfur (S), and/or nitrogen (N) atom, as in the groups—SH, ═NH, and NH₂. Isocyanate (—NCO) functionality may also be used.Presently preferred polycyclic-group-containing reactants have two ormore (more preferably two) active hydrogen or isocyanate groups.Carboxylic acid groups, anhydride groups, isocyanate groups, hydroxylgroups, and combinations thereof, are presently preferred. Examples ofsome suitable polycyclic-containing reactants includepolycyclic-containing polyols (e.g. tricyclodecane dimethanol (TCDM),isosorbide, isomannide, or isoidide); polycyclic-containing carboxylicacids and/or anhydrides (e.g., nadic acid or anhydride);polycyclic-containing polyamines (e.g., tricyclodecane diamine); andpolycyclic-containing polyisocyanates (e.g., tricyclodecanediisocyanate). Difunctional polycyclic-containing reactants arepreferred in certain embodiments.

It is also contemplated that a preformed polymer may be post-modified toinclude one or more polycyclic groups.

In some embodiments, one or more polycyclic groups are derived fromplant-based materials such as, for, example corn. Examples of suitableplant-based materials include compounds derived from sugars, withanhydrosugars being preferred, and dianhydrosugars being especiallypreferred. Examples of suitable such compounds include bisanhydrodexitolor isohexide compounds such as, for example:

isosorbide (whose structure is depicted above), isomannide, isoidide,and derivatives or combinations thereof.

In some embodiments, the one or more polycyclic groups are unsaturatedbicyclic groups represented by the IUPAC (International Union of Pureand Applied Chemistry) nomenclature of Expression (I) below:bicyclo[x.y.z]alkeneIn Expression (I):

-   -   x is an integer having a value of 2 or more,    -   y is an integer having a value of 1 or more,    -   z is an integer having a value of 0 or more, and    -   the term alkene refers to the IUPAC nomenclature designation        (e.g., hexene, heptene, heptadiene, octene, etc.) for a given        bicyclic molecule and denotes that that the bicyclic group        includes one or more double bonds (more typically one or more        carbon-carbon double bonds).

In some embodiments, z in Expression (I) is 1 or more. In other words,in certain embodiments the bicyclic groups are bridged bicyclic groups.By way of example, bicyclo[4.4.0]decane is not a bridged bicyclic.

In some embodiments, x has a value of 2 or 3 (more preferably 2) andeach of y and z independently have a value of 1 or 2.

The bicyclic structures represented by Expression (I) include one ormore carbon-carbon double bonds (e.g., 1, 2, 3, etc.).

Non-limiting examples of some suitable unsaturated bicyclic groupsrepresented by Expression (I) include bicyclo[2.1.1]hexene,bicyclo[2.2.1]heptene (i.e., norbornene), bicyclo[2.2.2]octene,bicyclo[2.2.1]heptadiene, and bicyclo[2.2.2]octadiene.Bicyclo[2.2.1]heptene is a presently preferred unsaturated bicyclicgroup.

It is contemplated that the bicyclic groups represented by Expression(I) may contain one or more heteroatoms (e.g., nitrogen, oxygen, sulfur,etc.) and may be substituted to contain one or more additionalsubstituents. For example, one or more cyclic groups (including, e.g.,pendant cyclic groups and ring groups fused to a ring of a bicyclicgroup) or acyclic groups may be attached to the bicyclic grouprepresented by Expression (I). Thus, for example, in some embodimentsthe bicyclic group of Expression (I) may be present in a tricyclic orhigher group. While the unsaturated bicyclic groups may be present as apart of a tricyclic or higher group, presently preferred unsaturatedbicyclic groups are not present in a tricyclic or higher group.

In some embodiments, some or all of the bicyclic groups may besaturated. Non-limiting examples of saturated bicyclics includesaturated homologs of the structures represented by Expression (I)(i.e., bicyclo[x.y.z]alkane, with x, y, and z as previously described)such as, for example, bicyclo[2.1.1]hexane, bicyclo[2.2.1]heptane,bicyclo[2.2.2]octane, and bicyclo[3.2.1]octane, bicyclo[4.3.2]undecane,bicyclo[5.2.0]nonane. In one embodiment, the bicyclic group includes twosaturated spiro, fused, and/or bridged rings and further includes one ormore unsaturated and/or aromatic organic groups attached to one of thesaturated rings.

In some embodiments, it may be advantageous for the polymer to includeone or more backbone segments having the below structure (Formula I):—X—R¹—X—;where:

-   -   each X is independently a polycyclic group;    -   R¹ is a divalent organic linking group (typically a substituted        or unsubstituted hydrocarbon linking group that may include one        or more heteroatoms in the chain); and    -   the two polycyclic groups are preferably closely spaced.

While not intending to be bound by any theory, it is believed that theinclusion of such backbone segments in a polymer may impart one or morebeneficial coating properties for coatings incorporating the polymer. R¹preferably has a chain length of 10 or less atoms (more preferably achain length of ≦5, ≦4, ≦3, ≦2, or 1 atoms) in the backbone chainconnecting the two X groups. In one embodiment, R¹ has the structure—C(R²)₂— where each R² is independently a hydrogen, a halogen, or anorganic group (e.g., a methyl group or a substituted or unsubstitutedhydrocarbon group that can include one or more heteroatoms), and whereinthe two R² groups can both be present in a ring group. A 2,2isopropylidene group is an example of a —C(R²)₂— group.

Segments having a structure of Formula I may be incorporated into apolymer of the invention using any suitable compound. For example, adi-functional dimer compound of the following Formula II may be used:Z—(R³)_(u)—X—R¹—X—(R³)_(u)—Z;where:

-   -   X and R¹ are as described above for Formula I;    -   each u is independently 0 or 1;    -   each R³, if present, is independently a divalent organic group        (typically a substituted or unsubstituted C1-C10 hydrocarbon        group that can include one or more heteroatoms); and    -   each Z is independently a reactive functional group, more        preferably a functional group capable of reacting with a        complimentary functional group to form a step-growth linkage        such as, for example, an amide, carbonate, ether, ester, urea,        or urethane linkage. Hydroxyl groups, carboxylic groups, and        isocyanate groups are preferred functional groups.

An example of a representative compound of Formula II is provided below:

where: the linking group is a 2,2 isopropylidene group that canindependently attach to any suitable carbon atom of the tricyclodecanegroups and the hydroxyl groups can independently attach to any suitablecarbon atom of the tricyclodecane groups. Such a compound may be formed,for example, through a dimerization reaction utilizing tricyclodecanedimethanol.

In certain preferred compounds, each of X and R¹ of Formulas I and IIare independently selected such that the unit length of the —X—R¹—X—structure is similar to that of a backbone epoxy unit produced by4,4′-isopropylidenediphenol (e.g., within 30%, 20%, 10%, etc. of theunit length of 4,4′-isopropylidenediphenol when present as a unit of apolyether polymer).

As discussed above, a combination of unsaturated bicyclic groups and atleast tricyclic groups is preferred in certain embodiments. It has beendiscovered that the inclusion of a suitable amount of each of thesegroups in the same binder polymer, preferably in combination withurethane linkages, can result in an improved balance of properties suchas excellent cure, excellent corrosion resistance, excellent blushresistance, and resistance to crazing. Comparable polyester polymersthat were prepared which omitted one of the groups (i.e., urethanelinkages, unsaturated bicyclic groups, or at least tricyclic groups)were observed to exhibit an inferior balance of coating propertiesrelative to polyester polymers that included suitable amounts of allthree groups.

In certain preferred embodiments, the polymer of the present inventionis a polyester polymer, more preferably a polyester-urethane polymer,that includes at least 1 wt-% (more preferably 1 to 35 wt-%) ofunsaturated bicyclic group containing monomer and at least 5 wt-% (morepreferably 5 to 50 wt-%) of at least tricyclic group containing monomer,based on the total solid weight of ingredients incorporated into thepolymer.

The polymer of the invention preferably has a glass transitiontemperature (Tg) of at least 30° C., more preferably at least 40° C.,even more preferably at least 50° C., and in some embodiments 70° C. ormore. In preferred embodiments, the Tg is less than 150° C., morepreferably less than 130° C., even more preferably less than 110° C.,and even more preferably less than 90° C. In one embodiment, the Tg isfrom about 70 to about 80° C. In embodiments where the polymer is to beused as a binder polymer for a food-contact coating composition, the Tgis preferably at least 50° C. In embodiments where the polymer includesboth a suitable amount of both bicyclic groups (more preferablyunsaturated bicyclic groups) and at least tricyclic groups (morepreferably tricyclic groups such as is provided by TCDM), the polymermay have any suitable Tg, but in presently preferred embodiments has aTg from 80 to 125° C.

The molecular weight of the polymer of the invention can vary dependingupon material choice and the desired end use. In preferred embodiments,the polymer has a number average molecular weight (Mn) of at least about1,000, more preferably at least about 1,500, and even more preferably atleast about 3,000. Preferably, the Mn of the polymer is less than about20,000, more preferably less than about 15,000, and even more preferablyless than about 10,000.

The backbone of the polymer may have any suitable terminal groups. Insome embodiments, the backbone of the polymer is hydroxyl-terminatedand/or carboxyl-terminated, more preferably hydroxyl-terminated.

The polymer may have any suitable hydroxyl number. Hydroxyl numbers aretypically expressed as milligrams of potassium hydroxide (KOH)equivalent to the hydroxyl content of 1 gram of the hydroxyl-containingsubstance. In certain preferred embodiments, the polymer has a hydroxylnumber of from 0 to about 150, even more preferably from about 5 toabout 100, and optimally from about 10 to about 80.

The polymer may have any suitable acid number. Acid numbers aretypically expressed as milligrams of KOH required to titrate a 1-gramsample to a specified end point. Methods for determining acid numbersare well known in the art. The range of suitable acid numbers may varydepending on a variety of considerations including, for example, whetherwater dispersibility is desired. In some embodiments, the polymer has anacid number of at least about 5, more preferably at least about 15, andeven more preferably at least about 30. Depending on the desired monomerselection, in certain embodiments (e.g., where a solvent-based coatingcomposition is desired), the polymer has an acid number of less thanabout 40, less than about 10, or less than about 5.

In some embodiments, the polymers of the invention are unsaturated.Preferred such polymers include unsaturated bicyclic groups such as, forexample, those having a structure pursuant to the aforementionedExpression (I). Iodine value is a useful measure for characterizing theaverage number of non-aromatic double bonds present in a material.Polymers of the invention may have any suitable iodine value to achievethe desired result. In embodiments where the polymer includesunsaturated bicyclic groups, the polymer preferably has an iodine valueof at least about 10, more preferably at least about 20, even morepreferably at least about 35, and optimally at least about 50. The upperrange of suitable iodine values is not limited, but in most embodimentsthe iodine value typically will not exceed about 120. Iodine values aretypically expressed in terms of centigrams of iodine per gram of resinand may be determined, for example, using the testing methodologyprovided in the Test Methods section of WO 2010/118356. In someembodiments, the polymer preferably includes a number of unsaturatedbicyclic groups sufficient to yield an iodine value of at least 5, atleast 10, at least 20, at least 35, or at least 50 (before factoring inthe portion of the total iodine value of the polymer attributable to anyother carbon-carbon double bonds that may optionally be present in thepolymer).

As previously discussed, in certain preferred embodiments the polymer isa polyester or polyester copolymer (e.g. polyester-urethane polymer).Examples of suitable polycarboxylic acids for use in forming polyesterportions of the polymer, or precursors thereof, include dicarboxylicacids and polyacids having higher acid functionality (e.g.,tricarboxylic acids, tetracarboxylic acids, etc.), precursors orderivatives thereof (e.g., an esterifiable derivative of apolycarboxylic acid, such as a dimethyl ester or anhydride), or mixturesthereof. Diacids are presently preferred. Suitable polycarboxylic acidsmay include, for example, maleic acid, fumaric acid, succinic acid,adipic acid, phthalic acid, tetrahydrophthalic acid,methyltetrahydrophthalic acid, hexahydrophthalic acid,methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid,azelaic acid, sebacic acid, tetrahydrophthalic acid, isophthalic acid,trimellitic acid, terephthalic acid, naphthalene dicarboxylic acid,cyclohexane-dicarboxylic acid, glutaric acid, dimer fatty acids, any ofthe other acids or anhydrides disclosed herein, anhydrides orderivatives thereof, and mixtures thereof. If desired, adducts ofpolyacid compounds (e.g., triacids, tetraacids, etc.) and monofunctionalcompounds may be used. An example of one such adduct is pyromelliticanhydride pre-reacted with benzyl alcohol.

Examples of suitable polyols for use in forming polyester portions ofthe polymer, or precursors thereof, include diols, polyols having threeor more hydroxyl groups (e.g., triols, tetraols, etc.), and combinationsthereof. Diols are presently preferred. Suitable polyols may include,for example, ethylene glycol, propylene glycol, 1,3-propanediol,glycerol, diethylene glycol, dipropylene glycol, triethylene glycol,trimethylolpropane, trimethylolethane, tripropylene glycol, neopentylglycol, pentaerythritol, 1,4-butanediol, hexylene glycol,cyclohexanedimethanol, a polyethylene or polypropylene glycol,isopropylidene bis(p-phenylene-oxypropanol-2), any of the other polyolsdisclosed herein, and mixtures thereof. If desired, adducts of polyolcompounds (e.g., triols, tetraols, etc.) and monofunctional compoundsmay be used. An example of one such adduct is dipentaerythritolpre-reacted with benzoic acid.

As previously discussed, in certain embodiments, the polymer of theinvention includes urethane linkages, preferably in a backbone of thepolymer. Polyester-urethane polymers (i.e., polymers including bothester and urethane linkages, and more preferably a plurality of eachlinkage type) are preferred polyurethane polymers. For sake ofconvenience, the term “polyurethane” is used in the discussion thatfollows and is intended to encompass polyester-urethane polymers.

Polyurethane polymers of the invention are typically formed via reactionof ingredients including an isocyanate (more preferably apolyisocyanate) and a polyol (more preferably a diol). The reactants canbe monomer reactants, oligomer reactants, polymer reactants, or acombination thereof. In some embodiments, one or both of thepolyisocyanate and the polyol are an oligomer or polymer. The reactantsused to produce the polyurethane polymer (e.g., one or more polyol andone or more polyisocyanate) may include any suitable ratio of isocyanateto hydroxyl groups. In some embodiments (e.g., where terminal hydroxylgroups are desired), the ratio of isocyanate to hydroxyl groups (NCO:OH)is preferably from 2:1 to 1:1. In certain other embodiments (e.g., whereterminal NCO groups are desired) the ratio of isocyanate to hydroxylgroups (NCO:OH) is preferably less than 1:1.

Preferred polyurethane polymers of the invention are formed via reactionof a polyisocyanate compound and a hydroxyl-functional polyesteroligomer or polymer, more preferably a hydroxyl-terminated polyesteroligomer or polymer. Preferred hydroxyl-functional polyester oligomersor polymers have a hydroxyl number of about 15 to about 200, morepreferably about 25 to about 150, and even more preferably about 35 toabout 115. Preferred polymers of the invention constitute at least 50wt-% (including, for example, >80 wt-%, >90 wt-%, >95 wt-%, etc.) ofpolyester segments.

The molecular weight of the polyester oligomer or polymer may varywidely depending upon, for example, the desired molecular weight of thepolyurethane polymer and/or the number of polyisocyanate molecules to beincorporated into the polyurethane polymer. For example, to prepare apolyurethane polymer having a desired molecular weight, two molecules ofa polyester oligomer or polymer having a molecular weight of “X” couldbe used or, alternatively, four molecules of a polyester oligomer orpolymer having a molecular weight of one-half X could be used. Incertain preferred embodiments, the polyester oligomer or polymer has anumber average molecular weight (Mn) of preferably about 500 to about10,000, more preferably about 750 to about 7,000, and even morepreferably about 1,000 to about 5,000.

The isocyanate may be any suitable compound, including an isocyanatecompound having 1 isocyanate group; a polyisocyanate compound having 2,3, or 4 or more isocyanate groups; or a mixture thereof. Suitablediisocyanates may include isophorone diisocyanate (i.e.,5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane); 5isocyanato-1-(2-isocyanatoeth-1-yl)-1,3,3-trimethylcyclohexane;5-isocyanato-1-(3-isocyanatoprop-1-yl)-1,3,3-trimethylcyclohexane;5-isocyanato-(4-isocyanatobut-1-yl)-1,3,3-trimethylcyclohexane;1-isocyanato-2-(3-isocyanatoprop-1-yl)cyclohexane;1-isocyanato-2-(3-isocyanatoeth-1-yl)cyclohexane;1-isocyanato-2-(4-isocy-anatobut-1 yl)cyclohexane;1,2-diisocyanatocyclobutane; 1,3-diisocyanatocyclobutane; 1,2diisocyanatocyclopentane; 1,3-diisocyanatocyclopentane;1,2-diisocyanatocyclohexane; 1,3-diisocyanatocyclohexane;1,4-diisocyanatocyclohexane; dicyclohexylmethane 2,4′-diisocyanate;trimethylene diisocyanate; tetramethylene diisocyanate; pentamethylenediisocyanate; hexamethylene diisocyanate; ethylethylene diisocyanate;trimethylhexane diisocyanate; heptamethylene diisocyanate;2-heptyl-3,4-bis(9-isocyanatononyl)-1-pentyl-cyclohexane; 1,2-, 1,4-,and 1,3-bis(isocyanatomethyl)cyclohexane; 1,2-, 1,4-, and 1,3bis(2-isocyanatoeth-1-yl)cyclohexane;1,3-bis(3-isocyanatoprop-1-yl)cyclohexane; 1,2-, 1,4- or1,3-bis(4-isocyanatobuty-1-yl)cyclohexane; liquidbis(4-isocyanatocyclohexyl)-methane; and derivatives or mixturesthereof.

In some embodiments, the isocyanate compounds are preferablynon-aromatic. Non-aromatic isocyanates are particularly desirable forcoating compositions intended for use on an interior surface of a foodor beverage container. Isophorone diisocyanate (IPDI) and hexamethylenediisocyanate (HMDI) are preferred non-aromatic isocyanates.

In some embodiments, at least some, or alternatively all, of the one ormore isocyanate compounds may be a partially blocked polyisocyanate.Certain embodiments may benefit from the inclusion of one or moreblocked isocyanate groups (e.g., deblockable isocyanate groups) in thepolyurethane polymer as a means for forming covalent linkages with othercomponents of the coating composition, including, for example, thepolyurethane polymer itself. Preferred partially blocked polyisocyanatescontain, on average: (i) at least about 1.5, more preferably at leastabout 1.8, and even more preferably at least about 2 free (or unblocked)isocyanate groups per molecule of partially blocked polyisocyanate andon average, and (ii) at least about 0.5, more preferably at least about0.7, and even more preferably at least about 1 blocked isocyanate groups(preferably deblockable isocyanate groups) per molecule of partiallyblocked polyisocyanate. Presently preferred blocking agents for formingdeblockable isocyanate groups include ε-caprolactam, diisopropylamine(DIPA), methyl ethyl ketoxime (MEKO), and mixtures thereof. For furtherdiscussion of suitable materials and methodologies relating to the useof partially blocked isocyanate compounds in forming polyurethanepolymers see co-pending PCT Application PCT/US2009/065848.

Preferred polyurethane polymers of the invention (more preferablypolyester-urethane polymers) include a sufficient number of urethanelinkages to provide the desired coating properties for the desired enduse. Such coating properties may include, for example, flexibility,abrasion resistance, and/or fabrication (e.g., to accommodate stampingprocesses used to form articles such as, for example, riveted beveragecan ends from coated planar metal substrate). Preferred such polymerspreferably include on average at least about 1 urethane linkages, morepreferably at least about 2 urethane linkages, and even more preferablyat least about 5 urethane linkages per molecule of the polymer. Whilethe number of urethane linkages present in the polymer is notparticularly restricted on the high end and may vary depending uponmolecular weight, in certain embodiments, the polymer includes onaverage less than about 15 urethane linkages, less than about 10urethane linkages, or less than about 7 urethane linkages per moleculeof the polymer.

Isocyanate content may be another useful measure of the number ofurethane linkages present in a polymer. In certain embodiments, thepolymer is formed from reactants including, based on total nonvolatiles,at least about 0.1 wt-%, more preferably at least about 1 wt-%, and evenmore preferably at least about 5 wt-% of an isocyanate compound. Theupper amount of suitable isocyanate compound concentration is notparticularly limited and will depend upon the molecular weight of theone or more isocyanate compounds utilized as reactants. Typically,however, the polymer is formed from reactants including, based on totalnonvolatiles, less than about 35 wt-%, more preferably less than about30 wt-%, and even more preferably less than about 25 wt-% of anisocyanate compound. Preferably, the isocyanate compound is incorporatedinto a backbone of the polymer via a urethane linkage, and morepreferably a pair of urethane linkages.

If desired, the polyurethane polymer may be optionally chain extended toincrease the molecular weight of the polymer. The resulting molecularweight may be outside the ranges recited previously herein. For example,after optional chain extension, the polyurethane polymer may have an Mnof at least 5,000, at least 10,000, or at least 30,000. Chain-extendingtechniques and materials such as those described in WO 2011/009040 canbe used. The polymer may be chain extended, for example, by reacting oneor more chain extenders with terminal and/or pendant isocyanate groupspresent on the polyurethane polymer. Suitable chain extenders mayinclude, for example, alkyl amino alcohols, cycloalkyl amino alcohols,heterocyclic amino alcohols, polyamines (e.g., ethylene diamine,diethylene triamine, triethylene tetra amine, melamine, etc.),hydrazine, substituted hydrazine, hydrazide, amides, water, othersuitable compounds having active hydrogen groups, ketimines preparedfrom any of the above amines, and combinations thereof. Preferably, thechain extension is conducted with organic polyamines, more preferablyaliphatic polyamines having at least two primary amine groups. Diaminesare preferred chain extenders. If a chain extender is utilized, thelinkage formed between the chain extender and the polyurethaneprepolymer is typically a urethane or urea linkage, more typically aurea linkage.

In an embodiment, the polymer of the invention is formed from reactantsincluding: 0 to 55 wt-% of an at least tricyclic group containingmonomer; 0 to 19 wt-% of an unsaturated bicyclic group containingmonomer; and 0 to 17 wt-% of an isocyanate compound. A representativesuch polymer is a polyester-urethane polymer formed from reactantincluding: 17 to 33 wt-% of TCDM (or other suitable at least tricyclicgroup containing monomer), 5 to 17 wt-% of nadic anhydride (or othersuitable unsaturated bicyclic group containing monomer), and 8 to 19wt-% of IPDI (or other suitable polyisocyanate compound). It iscontemplated that one or more of the aforementioned monomers may bepresent in an oligomer or polymer reactant used to form the polymer, inwhich case the aforementioned weight percentages refer to the totalweight of the structural units of the oligomer or polymer reactantderived from the specified monomer relative to the total weight of thefinal polymer.

If water dispersibility is desired, the polymer can be made waterdispersible using any suitable means, including the use of non-ionicwater-dispersing groups, salt groups (e.g., anionic and/or cationic saltgroups), surfactants, or a combination thereof. Preferredwater-dispersible polymers contain a suitable amount of salt-containing(e.g., anionic and/or cationic salt groups) and/or salt-forming groupsto facilitate preparation of an aqueous dispersion or solution. Suitablesalt-forming groups may include neutralizable groups such as acidic orbasic groups. At least a portion of the salt-forming groups may beneutralized to form salt groups useful for dispersing the polymer intoan aqueous carrier. Acidic or basic salt-forming groups may beintroduced into the polymer by any suitable method.

Non-limiting examples of anionic salt groups include neutralized acid oranhydride groups, sulphate groups (—OSO₃ ⁻), phosphate groups (—OPO₃ ⁻),sulfonate groups (—SO₂O⁻), phosphinate groups (—POO⁻), phosphonategroups (—PO₃ ⁻), and combinations thereof. Non-limiting examples ofsuitable cationic salt groups include:

(referred to, respectively, as quaternary ammonium groups, quaternaryphosphonium groups, and tertiary sulfate groups) and combinationsthereof. Non-limiting examples of non-ionic water-dispersing groupsinclude hydrophilic groups such as ethylene oxide groups. Compounds forintroducing the aforementioned groups into polymers are known in theart. In some embodiments, a water-dispersible polymer of the inventionmay be achieved through inclusion of a sufficient number of carboxylicacid groups in the polymer. Non-limiting examples of suitable materialsfor incorporating such groups into the polymer include anhydrides orpolyanhydrides such as tetrahydrophthalic anhydride, pyromelliticanhydride, pyromellitic dianhydride, succinic anhydride, trimilleticanhydride (“TMA”), and mixtures thereof. In one embodiment, ahydroxyl-terminated polyester polymer or oligomer having one or morependant hydroxyl groups is reacted with an anhydride such as TMA toproduce a hydroxyl-terminated polyester having carboxylic functionality.The conditions of the reaction are preferably controlled, including thetemperature, to avoid gelling. The resulting carboxylic-functionalpolyester oligomer or polymer is neutralized (e.g., using a base such asan amine) to produce an aqueous dispersion. In some embodiments, it iscontemplated that water dispersibility may be provided through use ofacid-functional ethylenically unsaturated monomers that have beengrafted onto the polymer, whereby a suitable number of theacid-functional groups are neutralized with base (such as, e.g., atertiary amine) to produce salt groups. See for example, U.S. Pat.Application No. 20050196629 for examples of such techniques.

Coating compositions of the invention may include any suitable amount ofpolymer of the invention to produce the desired result. In preferredembodiments, the coating composition includes at least a film-formingamount of the polycyclic-functional polymer of the invention, preferablyfrom about 10 to about 100 wt-%, more preferably at least about 40 wt-%,even more preferably at least about 60 wt-%, and even more preferably atleast about 70 wt-% of the polycyclic-functional polymer, based on thetotal nonvolatile weight of the coating composition. Preferably, thecoating composition includes less than about 99 wt-%, more preferablyless than about 95 wt-%, and even more preferably less than about 80wt-% of polycyclic-functional polymer, based on the total nonvolatileweight of the coating composition.

Preferred polymers and/or coating compositions of the invention arepreferably substantially free, more preferably essentially free, evenmore preferably essentially completely free, and optimally completelyfree of mobile bisphenol A (BPA) and aromatic glycidyl ether compounds(e.g., diglycidyl ethers of bisphenol (BADGE), diglycidyl ethers ofbisphenol F (BFDGE), and epoxy novalacs). In certain preferredembodiments, the polymer and/or coating composition of the inventionsare preferably substantially free, more preferably essentially free,even more preferably essentially completely free, and optimallycompletely free of bound BPA and aromatic glycidyl ether compounds(e.g., BADGE, BFDGE and epoxy novalacs).

In some embodiments, the polymer and/or coating composition is at leastsubstantially “epoxy-free,” more preferably “epoxy-free.” The term“epoxy-free,” when used herein in the context of a polymer, refers to apolymer that does not include any “epoxy backbone segments” (i.e.,segments formed from reaction of an epoxy group and a group reactivewith an epoxy group). Thus, for example, a polymer made from ingredientsincluding an epoxy resin would not be considered epoxy-free. Similarly,a polymer having backbone segments that are the reaction product of abisphenol (e.g., bisphenol A, bisphenol F, bisphenol S, 4,4′dihydroxybisphenol, etc.) and a halohdyrin (e.g., epichlorohydrin) would not beconsidered epoxy-free. However, a vinyl polymer formed from vinylmonomers and/or oligomers that include an epoxy moiety (e.g., glycidylmethacrylate) would be considered epoxy-free because the vinyl polymerwould be free of epoxy backbone segments. The coating composition of theinvention is also preferably at least substantially epoxy-free, morepreferably epoxy-free.

In some embodiments, the coating composition of the invention is“PVC-free.” That is, each composition preferably contains less than 2wt-% of vinyl chloride materials, more preferably less than 0.5 wt-% ofvinyl chloride materials, and even more preferably less than 1 ppm ofvinyl chloride materials.

When present, the concentration of one or more optional crosslinkers inthe coating composition may vary depending upon the desired result. Forexample, in some embodiments, the coating composition may contain fromabout 0.01 to about 50 wt-%, more preferably from about 5 to about 50wt-%, even more preferably from about 10 to about 40 wt-%, and optimallyfrom about 15 to about 30 wt-% of one or more crosslinkers, by weight ofnonvolatile material in the coating composition.

Any suitable crosslinker or combination of crosslinkers can be used. Forexample, phenolic crosslinkers (e.g., phenoplasts), amino crosslinkers(e.g., aminoplasts), blocked isocyanate crosslinkers, epoxy-functionalcrosslinkers, and combinations thereof, may be used. Preferredcrosslinkers are at least substantially free, more preferably completelyfree, of bound BPA and aromatic glycidyl ethers.

Examples of suitable phenolic crosslinkers include the reaction productsof aldehydes with phenols. Formaldehyde and acetaldehyde are preferredaldehydes. Non-limiting examples of suitable phenols that can beemployed include phenol, cresol, p-phenylphenol, p-tert-butylphenol,p-tert-amylphenol, cyclopentylphenol, cresylic acid, BPA (not presentlypreferred), and combinations thereof.

Amino crosslinker resins (e.g., aminoplasts) are typically thecondensation products of aldehydes (e.g., such as formaldehyde,acetaldehyde, crotonaldehyde, and benzaldehyde) with amino- oramido-group-containing substances (e.g., urea, melamine andbenzoguanamine). Suitable amino crosslinking resins include, forexample, benzoguanamine-formaldehyde-based resins,melamine-formaldehyde-based resins (e.g., hexamethonymethyl melamine),etherified melamine-formaldehyde, urea-formaldehyde-based resins, andmixtures thereof.

Condensation products of other amines and amides can also be employedsuch as, for example, aldehyde condensates of triazines, diazines,triazoles, guanadines, guanamines and alkyl- and aryl-substitutedmelamines. Some examples of such compounds are N,N′-dimethyl urea,benzourea, dicyandimide, formaguanamine, acetoguanamine, glycoluril,ammelin 2-chloro-4,6-diamino-1,3,5-triazine,6-methyl-2,4-diamino-1,3,5-triazine, 3,5-diaminotriazole,triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine,3,4,6-tris(ethylamino)-1,3,5-triazine, and the like. While the aldehydeemployed is typically formaldehyde, other similar condensation productscan be made from other aldehydes, such as acetaldehyde, crotonaldehyde,acrolein, benzaldehyde, furfural, glyoxal and the like, and mixturesthereof.

Suitable commercially available amino crosslinking resins include, forexample, CYMEL 301, CYMEL 303, CYMEL 370, CYMEL 373, CYMEL 1125, CYMEL1131, CYMEL 5010 and MAPRENAL MF 980 (all available from CytecIndustries Inc., West Patterson, N.J.), and URAMEX BF 892 (availablefrom DSM, Netherlands).

Non-limiting examples of blocked isocyanate crosslinkers includealiphatic and/or cycloaliphatic blocked polyisocyanates such as HDI(hexamethylene diisocyanate), IPDI (isophorone diisocyanate), TMXDI(bis[4-isocyanatocyclohexyl]methane), H₁₂MDI (tetramethylene-m-xylidenediisocyanate), TMI (isopropenyldimethyl-benzylisocyanate) and dimers ortrimers thereof. Suitable blocking agents include, for example,n-butanone oxime, ε-caprolactam, diethyl malonate, and secondary amines.Non-limiting examples of suitable commercially available blockedisocyanate crosslinkers include VESTANAT B 1358 A, VESTANAT EP B 1186 A,VESTANA EP B 1299 SV (all available from Degussa Corp., Marl, Germany);and DESMODUR VPLS 2078 and DESMODURBL 3175 (available from Bayer A. G.,Leverkusen, Germany). In some embodiments, blocked isocyanates may beused that have an Mn of at least about 300, more preferably at leastabout 650, and even more preferably at least about 1,000.

In embodiments where the polymer includes unsaturated bicyclic groups,and more preferably unsaturated bridged bicyclic groups such asnorbornene groups, it may be advantageous to utilize the polymer incombination with a phenolic crosslinker, with resole phenoliccrosslinkers being particularly preferred. While not intending to bebound by any theory, cured packaging coatings formulated using such acombination of polymer and resole-type phenolic crosslinker (with orwithout additional crosslinkers such as, e.g., non-resole phenoliccrosslinkers, amino crosslinkers, and/or blocked isocyanate) have beenobserved to exhibit superior coating properties relative to comparablecured packaging coatings formulated without resole-type phenoliccrosslinkers. In preferred embodiments, upon curing of the coating, theresole-type phenolic crosslinker is believed to form a covalent bondwith the unsaturated bicyclic group, resulting in the formation of acrosslinked polymer network including both the phenolic crosslinker andthe polymer. While not intending to be bound by any theory, this isbelieved to be responsible, at least in part, for the enhanced coatingproperties exhibited by certain preferred packaging coatings of theinvention relative to certain conventional packaging coatingscontaining, for example, polyester and phenolic resins that do not form,or do not appreciably form, such a polymer network with each other.

One preferred optional ingredient is a catalyst to increase the rate ofcure and/or the extent of crosslinking. Non-limiting examples ofcatalysts, include, but are not limited to, strong acids (e.g.,dodecylbenzene sulphonic acid (DDBSA), available as CYCAT 600 fromCytec, methane sulfonic acid (MSA), p-toluene sulfonic acid (pTSA),dinonylnaphthalene disulfonic acid (DNNDSA), and triflic acid),quaternary ammonium compounds, phosphorous compounds, tin, titanium, andzinc compounds, and combinations thereof. Specific examples include, butare not limited to, a tetraalkyl ammonium halide, a tetraalkyl ortetraaryl phosphonium iodide or acetate, tin octoate, zinc octoate,triphenylphosphine, and similar catalysts known to persons skilled inthe art. If used, a catalyst is preferably present in an amount of atleast 0.01 wt-%, and more preferably at least 0.1 wt-%, based on theweight of nonvolatile material in the coating composition. If used, acatalyst is preferably present in an amount of no greater than 3 wt-%,and more preferably no greater than 1 wt-%, based on the weight ofnonvolatile material in the coating composition.

If desired, coating compositions of the invention may optionally includeother additives that do not adversely affect the coating composition ora cured coating resulting therefrom. The optional additives arepreferably at least substantially free of mobile and/or bound BPA andaromatic glycidyl ether compounds (e.g., BADGE, BFDGE and epoxy novalaccompounds) and are more preferably completely free of such compounds.Suitable additives include, for example, those that improve theprocessability or manufacturability of the composition, enhancecomposition aesthetics, or improve a particular functional property orcharacteristic of the coating composition or the cured compositionresulting therefrom, such as adhesion to a substrate. Additives that maybe included are carriers, additional polymers, emulsifiers, pigments,metal powders or paste, fillers, anti-migration aids, anti-microbials,extenders, curing agents, lubricants, coalescents, wetting agents,biocides, plasticizers, crosslinking agents, antifoaming agents,colorants, waxes, anti-oxidants, anticorrosion agents, flow controlagents, thixotropic agents, dispersants, adhesion promoters, UVstabilizers, scavenger agents or combinations thereof. Each optionalingredient can be included in a sufficient amount to serve its intendedpurpose, but preferably not in such an amount to adversely affect acoating composition or a cured coating resulting therefrom.

Any suitable carrier may be used to prepare coating compositions of theinvention. Suitable carriers include carrier liquids such as organicsolvents, water, and mixtures thereof. Preferably, the liquid carrier(s)are selected to provide a dispersion or solution of the polymer of theinvention for further formulation. Suitable organic solvents includealiphatic hydrocarbons (e.g., mineral spirits, kerosene, high flashpointVM&P naphtha, and the like); aromatic hydrocarbons (e.g., benzene,toluene, xylene, solvent naphtha 100, 150, 200 and the like); alcohols(e.g., ethanol, n-propanol, isopropanol, n-butanol, iso-butanol and thelike); ketones (e.g., acetone, 2-butanone, cyclohexanone, methyl arylketones, ethyl aryl ketones, methyl isoamyl ketones, and the like);esters (e.g., ethyl acetate, butyl acetate and the like); glycols (e.g.,butyl glycol); glycol ethers (e.g., ethylene glycol monomethyl ether,ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,propylene glycol monomethyl ether, methoxypropanol and the like); glycolesters (e.g., butyl glycol acetate, methoxypropyl acetate and the like);and mixtures thereof.

If present, the amount of liquid carrier included in the coatingcomposition will vary, for example, depending upon the applicationmethod and the desired amount of solids. Preferred embodiments of thecoating composition include at least 30 wt-% of liquid carrier, morepreferably at least 35 wt-%, and even more preferably at least 45 wt-%.In such embodiments, the coating composition will typically include lessthan 85 wt-% of liquid carrier, more typically less than 80 wt-% ofliquid carrier.

In some embodiments, the coating composition is a solvent-based coatingcomposition that preferably includes no more than a de minimus amount(e.g., 0 to 2 wt-%) of water. In other embodiments, the coatingcomposition can include a substantial amount of water.

In some embodiments, the coating composition of the invention is awater-based varnish. As already discussed, the polymer of the inventionmay include water-dispersing groups such as salt groups. In someembodiments, preferably at least about 50 wt-% of the liquid carriersystem is water, more preferably at least about 60 wt-% is water, andeven more preferably at least about 75 wt-% is water. Certain coatingcompositions of the invention may include at least about 10 wt-% ofwater, more preferably at least about 20 wt-% of water, and even morepreferably at least about 40 wt-% of water (in some embodiments about 50wt-% or more of water), based on the total weight of the coatingcomposition.

Coating compositions of the invention may be prepared by conventionalmethods in various ways. For example, the coating compositions may beprepared by simply admixing the polymer of the invention, optionalcrosslinker and any other optional ingredients, in any desired order,with sufficient agitation. The resulting mixture may be admixed untilall the composition ingredients are substantially homogeneously blended.Alternatively, the coating compositions may be prepared as a liquidsolution or dispersion by admixing an optional carrier liquid, thepolymer of the invention, optional crosslinker, and any other optionalingredients, in any desired order, with sufficient agitation. Anadditional amount of carrier liquid may be added to the coatingcompositions to adjust the amount of nonvolatile material in the coatingcomposition to a desired level.

The total amount of solids present in coating compositions of theinvention may vary depending upon a variety of factors including, forexample, the desired method of application. Presently preferred coatingcompositions include at least about 20, more preferably at least about30, and even more preferably at least about 40 wt-% of solids, based onthe total weight of the coating composition. In certain preferredembodiments, the coating composition includes less than about 80, morepreferably less than about 70, and even more preferably less than about65 wt-% of solids, based on the total weight of the coating composition.The solids of the coating composition may be outside the above rangesfor certain types of applications.

Cured coatings of the invention preferably adhere well to metal (e.g.,steel, tin-free steel (TFS), tin plate, electrolytic tin plate (ETP),aluminum, etc.) and provide high levels of resistance to corrosion ordegradation that may be caused by prolonged exposure to products such asfood or beverage products. The coatings may be applied to any suitablesurface, including inside surfaces of containers, outside surfaces ofcontainers, container ends, and combinations thereof.

The coating composition of the invention can be applied to a substrateusing any suitable procedure such as spray coating, roll coating, coilcoating, curtain coating, immersion coating, meniscus coating, kisscoating, blade coating, knife coating, dip coating, slot coating, slidecoating, and the like, as well as other types of premetered coating.

The coating composition can be applied on a substrate prior to, orafter, forming the substrate into an article. In some embodiments, atleast a portion of a planar substrate is coated with one or more layersof the coating composition of the invention, which is then cured beforethe substrate is formed into an article (e.g., via stamping, drawing, ordraw-redraw).

After applying the coating composition onto a substrate, the compositioncan be cured using a variety of processes, including, for example, ovenbaking by either conventional or convectional methods. The curingprocess may be performed in either discrete or combined steps. Forexample, the coated substrate can be dried at ambient temperature toleave the coating composition in a largely un-crosslinked state. Thecoated substrate can then be heated to fully cure the coatingcomposition. In certain instances, the coating composition can be driedand cured in one step. In preferred embodiments, the coating compositionof the invention is a heat-curable coating composition.

The curing process may be performed at any suitable temperature,including, for example, temperatures in the range of about 180° C. toabout 250° C. If metal coil is the substrate to be coated, curing of theapplied coating composition may be conducted, for example, by subjectingthe coated metal to an elevated temperature environment of about 210° C.to about 232° C. for a suitable time period (e.g., about 15 to 30seconds). If metal sheeting is the substrate to be coated (e.g., such asused to make three-piece food cans), curing of the applied coatingcomposition may be conducted, for example, by subjecting the coatedmetal to an elevated temperature environment of about 190° C. to about210° C. for a suitable time period (e.g., about 8 to about 12 minutes).

Coating compositions of the invention may be useful in a variety ofcoating applications. As previously discussed, the coating compositionsare particularly useful as adherent coatings on interior or exteriorsurfaces of metal packaging containers. Non-limiting examples of sucharticles include closures (including, e.g., internal surfaces oftwist-off caps for food and beverage containers); internal crowns; twoand three-piece cans (including, e.g., food and beverage containers);shallow drawn cans; deep drawn cans (including, e.g., multi-stage drawand redraw food cans); can ends (including, e.g., easy open can ends orbeverage can ends); monobloc aerosol containers; medical packagingcontainers such as metered dose inhaler (“MDI”) cans for use in storingand administering pharmaceuticals; and general industrial containers,cans, and can ends. Preferred coating compositions of the invention areparticularly suited for use on interior or exterior surfaces of metalfood or beverage containers, including as food-contact coatings.

Preferred food-contact coating compositions of the invention, whensuitably cured on metal packaging substrate exhibit one or more of thefollowing properties after retort in a test substance such as one usedin the below Examples: an adhesion of at least 8, more preferably atleast 9, and optimally 10; a blush resistance of at least 8, and morepreferably at least 9; a wedge bend of at least 70%; and/or at least 30MEK double rubs. Suitable methods for testing these properties aredescribed in the below Test Methods Section.

Some additional non-limiting embodiments of the invention are providedbelow.

-   A. A composition comprising: a polymer having a backbone or pendant    polycyclic group (more preferably a backbone polycyclic group).-   B. An article, comprising: a metal substrate having the composition    of Embodiment A applied on at least a portion of a major surface of    the metal substrate.-   C. A method comprising: providing the composition of Embodiment A,    and applying the composition on at least a portion of a metal    substrate.-   D. Any of Embodiments A-C, wherein the polymer is a polyester    polymer or a polyester-urethane polymer having both backbone ester    and urethane linkages.-   E. Any of Embodiments A-D, wherein the one or more polycyclic groups    constitute at least about 10 wt-%, more preferably at least about 20    wt-%, and even more preferably at least 30 wt-% of the polymer,    based on the weight percent of polycyclic-group-containing monomer    relative to the total weight of the polymer.-   F. Any of Embodiments A-E, wherein the one or more polycyclic groups    comprises a saturated bicyclic group (which can optionally include    one or more unsaturated and/or aromatic organic groups attached to    either of the saturated spiro, fused, and/or bridged rings of the    bicyclic group), an unsaturated bicyclic group, an aromatic bicyclic    group, an at least tricyclic group, or a combination thereof.-   G. Any of Embodiments A-F, wherein the polymer has a glass    transition temperature of at least 50° C., and more preferably at    least 70° C.-   H. Any of Embodiments A-G, wherein the one or more polycyclic groups    is a saturated group.-   I. Any of Embodiments A-H, wherein the one or more polycyclic groups    is a bicyclic group.-   J. A composition, article, or method of Embodiment I, wherein one or    both cyclic groups of the bicyclic group are aromatic.-   K. A composition, article, or method of Embodiment I, wherein one or    both cyclic groups of the bicyclic group are unsaturated.-   L. Any of Embodiments A-H, wherein the one or more polycyclic groups    is an at least tricyclic group.-   M. The composition, article, or method of Embodiment L, where the at    least tricyclic group includes a substituted or unsubstituted    tricyclodecane group.-   N. The composition, article, or method of Embodiment M, wherein the    tricyclodecane group is provided by tricyclodecane dimethanol,    tricyclodecane diamine, tricyclodecane diisocyanate, or a derivative    or mixture thereof.-   O. Any of Embodiments A-M, wherein the polycyclic group includes one    or more heteroatoms in a ring of the polycyclic group.-   P. Any of Embodiments A-I, wherein the polycyclic group is derived    from a sugar feedstock.-   Q. The composition, article, or method of Embodiment P, wherein the    polycyclic group is derived from isosorbide, isomannide, or    isoiodide.-   R. Any of Embodiments A-Q, wherein the coating composition, based on    total weight solids, includes at least 10 wt-%, more preferably at    least 40 wt-%, and even more preferably at least 60 wt-% of the    polymer.-   S. Any of Embodiments A-R, wherein the coating composition further    comprises one or more crosslinkers, preferably in an amount of at    least 5 wt-%.-   T. The composition, article, or method of Embodiment S, wherein the    one or more crosslinkers comprises an amino crosslinker, a phenolic    crosslinker, a blocked isocyanate crosslinker, or a mixture thereof.-   U. Any of Embodiments A-T, wherein the coating composition further    comprises a liquid carrier.-   V. The composition, article, or method of Embodiment U, wherein the    coating composition is a water-based coating composition and/or a    solvent-based coating composition.-   W. Any of Embodiments A-V, wherein the polymer includes both: (i)    one or more bicyclic groups (e.g., saturated bicyclic groups,    unsaturated bicyclic groups, one or more of each of saturated and    unsaturated bicyclic groups, etc.), more preferably one or more    unsaturated bicyclic groups such as, e.g., one or more substituted    or unsubstituted norbornene groups, and (ii) one or more at least    tricyclic groups (e.g., one or more substituted or unsubstituted    tricyclodecane groups).

Test Methods

Unless indicated otherwise, the following test methods were utilized inthe Examples that follow.

A. Retort Method

This test provides an indication of an ability of a coating to withstandconditions frequently associated with food or beverage preservation orsterilization. Coated substrate samples (in the form, e.g., of ETP orTFS flat panels) are placed in a vessel and partially immersed in a testsubstance. While immersed in the test substance, the coated substratesamples are placed in an autoclave and subjected to heat of 130° C. andpressure of 1 atm above atmospheric pressure for a time period of 60minutes. Just after retort, the coated substrate samples are tested foradhesion, blush resistance, and/or stain resistance.

B. Adhesion Test

Adhesion testing is performed to assess whether the coating compositionsadhere to the coated substrate. The Adhesion Test is performed accordingto ASTM D 3359—Test Method B, using SCOTCH 610 tape, available from 3MCompany of Saint Paul, Minn. Adhesion is generally rated on a scale of0-10 where a rating of “10” indicates no adhesion failure, a rating of“9” indicates 90% of the coating remains adhered, a rating of “8”indicates 80% of the coating remains adhered, and so on. A coating isconsidered herein to satisfy the Adhesion Test if it exhibits anadhesion rating of at least 8.

C. Blush Resistance Test

Blush resistance measures the ability of a coating to resist attack byvarious solutions. Typically, blush is measured by the amount of waterabsorbed into a coated film. When the film absorbs water, it generallybecomes cloudy or looks white. Blush is generally measured visuallyusing a scale of 0-10 where a rating of “10” indicates no blush, arating of “8” indicates slight whitening of the film, and a rating of“5” indicates whitening of the film, and so on.

D. Solvent Resistance Test

The extent of “cure” or crosslinking of a coating is measured as aresistance to solvents, such as methyl ethyl ketone (MEK) or isopropylalcohol (IPA). This test is performed as described in ASTM D 5402-93.The number of double rubs (i.e., one back-and-forth motion) is reported.Preferably, the MEK solvent resistance is at least 30 double rubs.

E. Wedge Bend Test

This test provides an indication of a level of flexibility of a coatingand an extent of cure. Test wedges are formed from coated rectangularmetal test sheets (which measured 12 cm long by 5 cm wide). Test wedgesare formed from the coated sheets by folding (i.e., bending) the sheetsaround a mandrel. To accomplish this, the mandrel is positioned on thecoated sheets so that it is oriented parallel to, and equidistant from,the 12 cm edges of the sheets. The resulting test wedges have a 6 mmwedge diameter and a length of 12 cm. To assess the wedge bendproperties of the coatings, the test wedges are positioned lengthwise ina metal block of a wedge bend tester and a 2.4 kg weight is dropped ontothe test wedges from a height of 60 cm.

The deformed test wedges are then immersed in a copper sulphate testsolution (prepared by combining 20 parts of CuSO₄.5H₂O, 70 parts ofdeionized water, and 10 parts of hydrochloric acid (36%)) for about 2minutes. The exposed metal is examined under a microscope and themillimeters of coating failure along the deformation axis of the testwedges was measured. The data is expressed as a wedge bend percentageusing the following calculation:100%×[(120 mm)−(mm of failure)]/(120 mm).

A mono-coat coating system is considered herein to satisfy the WedgeBend Test if it exhibits a wedge bend percentage of 70% or more, whereasa two-coat coating system is considered herein to satisfy the test if itexhibits a wedge bend percentage of 85% or more.

F. Porosity Test

This test provides an indication of the level of flexibility of acoating. Moreover, this test measures the ability of a coating to retainits integrity as it undergoes the formation process necessary to producea food or beverage can end. In particular, it is a measure of thepresence or absence of cracks or fractures in the formed end. To besuitable for food or beverage can end applications, a coatingcomposition should preferably exhibit sufficient flexibility toaccommodate the extreme contour of the rivet portion of the easy openfood or beverage can end.

The end is typically placed on a cup filled with an electrolytesolution. The cup is inverted to expose the surface of the end to theelectrolyte solution. The amount of electrical current that passesthrough the end is then measured. If the coating remains intact (nocracks or fractures) after fabrication, minimal current will passthrough the end.

For the present evaluation, fully converted 206 standard opening canends are exposed for a period of 4 seconds to an electrolyte solutioncomprised of 1% NaCl by weight in deionized water. Metal exposures aremeasured using a WACO Enamel Rater II, available from theWilkens-Anderson Company, Chicago, Ill., with an output voltage of 6.3volts. The measured electrical current, in milliamps, is reported. Endcontinuities are typically tested initially and then after the ends aresubjected to pasteurization or retort.

A coating is considered herein to satisfy the Porosity Test if it passesan electric current (after end formation) of less than about 10milliamps (mA) when tested as described above.

EXAMPLES

The following examples are offered to aid in understanding of thepresent invention and are not to be construed as limiting the scopethereof. Unless otherwise indicated, all parts and percentages are byweight, and all molecular weights are number average molecular weights.

Example 1 Polyester-Urethane Including Tricyclodecane Groups

Tricyclodecane dimethanol (455 grams (“g”)), 1,4 butane diol (85 g),terephthalic acid (490 g), polymerization catalyst (1.25 g), andAROMATIC 150 solvent (50 g) were added to a glass reaction flaskequipped with a stirrer, nitrogen inlet and reflux condenser. Thecondenser was further equipped with a Dean-Stark flask to capture andquantify the water evolved during the reaction. The reactor was set for225-235° C. After approximately 12 hours, the acid value of theresulting polyester polymer was approximately 42.3 mg KOH/g. Themolecular weight of this prepolymer was about 2650 g/mol. To thispolymer was added dibutyl tin dilaureate (DBTDL) (1.5 g) and isophoronediisocyanate (IPDI) (150 g). This reaction was allowed to proceed at100° C. until all of the isocyanate was consumed. The final molecularweight was 15,400 Daltons.

Example 2 Polyester-Urethane Including Isosorbide Groups

Neopentyl glycol (566 g), monoethylenglycol (91 g), isosorbide (328 g)(from Archers Daniels Midland), dimer fatty acid (654 g) (RADIACID 960product from Oleon), isophthalic acid (1152 g), and polymerizationcatalyst (1.25 g) were added to a glass reaction flask equipped with astirrer, nitrogen inlet, partial condenser, decanter and refluxcondenser. The contents of the glass were progressively heated to 240°C. while the temperature at the top of the partial condenser was lessthan 102° C. and the contents were maintained at 240° C. until the acidvalue was about 15 to 20. Esterification water was removed continuously.When the acid value was about 15 to 20, the product was cooled to 180°C., the partial condenser was removed and replaced by a total condenserequipped with a Dean-Stark flask to capture and quantify the waterevolved during the reaction. Xylene (131 g) was added. The product wasthen slowly heated to maintain a gentle reflux. The temperature of theproduct was increased to 225° C.-235° C. When the acid value was in therange of 5-10 and the cut viscosity (75% in Xylene) was in the range of110-120 Poises at 25° C., the product was cooled. When the temperatureof the product reached 200° C., the non-volatile content (NVC) wasreduced to 70% with SOLVESSO 100 solvent.

The resulting 70% polyester product (1,342 g) was added to a glassreaction flask equipped with a stirrer and nitrogen inlet and heated to95-100° C. Partially blocked polyisocyanate (described below) (365 g)was added over 10 minutes and immediately after SOLVESSO 100 solvent (75g) was added. The product was held at 95-100° C. until the cut viscosityat 55% NVC in Butanol reached 25-30 Poises at 25° C. and NCO content wasless than 0.05%.

Then, butanol (162 g) was added and the mixture was mixed for 30 minutesat 80° C. (NCO content=0) and finally Solvesso 100 solvent (162 g) wasadded to produce a solution of polyester-urethane polymer at 55% solids.

The partially blocked polyisocyanate was prepared as follows. VESTANAT1890 (742 g) (polyisocyanate trimer at 70% in butyl acetate and SOLVESSO100 solvent, from Evonik) was heated at 70° C. in a glass reaction flaskequipped with a stirrer, nitrogen inlet and reflux condenser.Caprolactam (81 g) was added over 5 minutes. The temperature wasincreased over 1 hour to 100° C. and maintained at 100° C. until the NCOcontent was about 7.2%. At 100° C., SOLVESSO 100 solvent (178 g) wasadded to obtain a solution having 60% NVC and a viscosity of 90-100seconds (Afnor 4, 25° C.).

Example 3 Polyester-Urethane Including Norbornene Groups

Cyclohexane dimethanol (CHDM) (485 g of a 90% solution in water),methylpropanediol (241.5 g), terephthalic acid (123 g), isophthalic acid(244.5 g), nadic anhydride (453 g), dibutyl tin oxide (1.5 g) (FASTCAT4201 catalyst from Atofina), and xylene (72 g) were added to a glassreaction flask equipped with a stirrer, nitrogen inlet and refluxcondenser. The condenser was further equipped with a Dean-Stark flask tocapture and quantify the water evolved during the reaction. The reactorwas set for a temperature in the range of 225-235° C. Afterapproximately 4 hours, the acid value of the resulting polyester polymerwas approximately 58.0 mg KOH/g. The molecular weight of this prepolymerwas about 1900 g/mol. To this prepolymer was added DBTDL (1.5 g) andIPDI (225 g). This reaction was allowed to proceed at 100° C. until allof the NCO was consumed (typically 4-5 hrs). The final molecular weightof the polyester-urethane polymer was 12,400 Daltons.

Example 4 Polyester-Urethane Including Norbornene Groups

CHDM (1449.7 g of a 90% solution in water), methylpropanediol (722.5 g),terephthalic acid (293.3 g), isophthalic acid (578 g), maleic anhydride(808.4 g), dibutyl tin oxide (4.2 g) (FASTCAT 4201 catalyst fromAtofina), and xylene (187 g) were added to a glass reaction flaskequipped with a stirrer, nitrogen inlet and reflux condenser. Thecondenser was further equipped with a Dean-Stark flask to capture andquantify the water evolved during the reaction. The reactor was set for230° C. After approximately 5 hours, the acid value of the resultingpolyester polymer was approximately 0.5 mg KOH/g resin. The temperatureof the reactor was reduced to approximately 160° C., at which pointdyclopentadiene (DCPD) (546.4 g) was added. The reactor was held anadditional 6 hours at 160° C. to complete the Diels-Alder reactionbetween the maleic unsaturation and the DCPD. The resulting structure isbelieved to resemble that of a material prepared from nadic anhydride.The resulting modified polyester polymer composition was 84% solids andhad an acid value of 1.4 mg KOH/g resin and an OH value of 56.6 mg KOH/gresin.

The modified polyester composition (1044.3 g) was added to a newreaction flask (same configuration as described above), along with IPDI(247.3 g) and dimethylol propionic acid (74.6 g). The temperature of theflask was maintained at about 100° C. and the reaction was continued forabout 6 hours, at which point butanol (307 g), butyl cellosolve (307 g),and cyclohexanone (1587 g) were added to the flask. The resultingpolyester-urethane polymer composition was 24% solids and had an acidvalue of 26.5 mg KOH/g resin.

The polyester-urethane polymer composition (100 g) was combined with aresole phenolic crosslinker resin (7.5 g). The resulting coatingformulation had a ratio, on a solids weight basis, of 80%polyester-urethane polymer and 20% phenolic resin.

A sample of the coating formulation of Example 4 was applied onto bothcommercially available ETP and TFS using a wound wire rod. The coatedsteel samples were baked about 12 minutes in a 402° F. (204° C.) oven todry and cure the coating. Once dried and cured, the film weight of thecoating was determined to be from about 4.5 to 5.0 mg of coating persquare inch of coated substrate (metric equivalent is 7 to 7.8 grams persquare meter). It was noted that the appearance of the coating wassmooth and glossy and had a goldish tint. Samples of the coatedsubstrate were fabricated into food can ends, with the coatingcomposition oriented as the internal coating. In addition, an analogousset of control food can ends were prepared from tin-plated and tin-freesteel coated with a conventional epoxy-based coating system that iscurrently used commercially as a high corrosion-resistant coating forthe interior of food can bodies and ends. Samples of both the controland experimental ends were then subjected to a variety of coatingproperty tests to evaluate the suitability of the coatings for use asfood-contact coatings for food or beverage cans. The cured coatingcomposition of Example 4 on ETP substrate exhibited good coatingproperties (e.g., comparable adhesion, blush resistance, stainresistance, and corrosion resistance as that of the commercial control).The cured coating composition of Example 4 on TFS substrate alsoexhibited good coating properties, although not quite as good as on ETPsubstrate (e.g., the adhesion and corrosion resistance were not asgood).

Example 5 Polyester-Urethane Including Norbornene Groups

TABLE 1 Ingredient Amount (weight parts) Neopentylglycol 742.81,4-cyclohexanedimethanol 424 Monoethylene glycol 119 Nadic Anhydride330 Isophthalic acid 1272 RADIACID 960 517 Dimer fatty acidOrganometallic catalyst 2 Hydroquinone methyl ether 2

The ingredients, in the amounts indicated above in Table 1, were chargedto a vessel equipped with a stirrer, reflux condenser, packed column,thermocouple, and a heating mantle. The mixture was heated to a maximumof 215° C. in such a manner that the temperature of the distillate atthe top of the partial condenser did not exceed 102° C. During thereaction, water was extracted by distillation until an acid number inthe range of 15 to 25 was reached. The polyester was then diluted withxylene to achieve an NVC of 94% by weight. The mixture was subjected toazeotropic distillation until an acid number of about 7 and a cutviscosity (75% in Xylene) around 150 Poises at 25° C. was reached. Afterthis step, the polyester was then diluted with SOLVESSO 100 solvent toreach an NVC of about 70% by weight. The viscosity was 63 Poises at 25°C., the acid number 7.3, and the NVC 69.4% (1 g, 60 minutes, 130° C.).

A partially blocked polyisocyanate compound was produced using theingredients listed in Table 2 below. The “dried” solvents in Table 2were mixed in advance with molecular sieves to avoid the presence ofwater. The partially blocked polyisocyanate compound was produced byfirst dissolving VESTANAT 1890/100 isocyanate tablets in dried xylene ina reactor at 100° C. After 1 hour of mixing, caprolactam was added inthe reactor. Complete dissolution of the caprolactam was observed aftera few minutes. The reactor was slowly heated to 100° C. Following theheating step, the % NCO (i.e., the weight of isocyanate groups dividedby the weight of the mixture in the reactor) of the mixture wasdetermined by titration and the reaction was stopped when thetheoretical % NCO was reached (i.e., in this case, the theoretical pointat which one-third of the NCO groups were calculated to be blocked andtwo-thirds were calculated to be unblocked), which took less than 2hours. The resulting mixture was then diluted with a second charge ofxylene to obtain a mixture having an NVC of 60% by weight.

TABLE 2 Ingredient Amount (wt-%) IPDI-based polyisocyanate trimer* 51.9Caprolactam 8.1 Dried xylene 15 Dried xylene charge 2 25 *VESTANATE1890/100 product available from Evonik.

The polyester-urethane polymer of Example 5 was produced as followsusing the ingredients in the amounts indicated in Table 3 below. Thepolyester of example 5 was charged in a reactor and heated up to 100° C.Then, the mixture including partially blocked polyisocyanate compoundwas added to the reactor over 10 minutes using an addition funnel, whichwas immediately flushed with SOLVESSO 100 solvent. The temperature wasmaintained around 100° C. and the reaction was continued until themixture exhibited a stable viscosity and the NCO content was less than0.01% (expressed in weight of NCO groups). Then butanol was added andthe mixture was homogenized at 80° C. for 30 minutes. Finally, theadditional SOLVESSO 100 solvent was added at 80° C. The viscosity wasaround 28 Poises at 25° C., no NCO was detectable by titration, and theNVC was 55.7% (1 g, 60 min, 130° C.).

TABLE 3 Ingredient Amount (wt-%) Polyester of Example 5 63.7 Partiallyblocked polyisocyanate 17.3 SOLVESSO 100 solvent^(A) 3.56 Butanol 7.06SOLVESSO 100 solvent^(B) 8.33 ^(A)First addition ^(B)Second addition

The coating composition of Example 5 was prepared by mixing theingredients included below in Table 4 using a stirrer. The viscosity ofthe resulting coating composition was adjusted with xylene to be in therange of 70 to 80 seconds as measured using a #4 Ford cup at 25° C. TheNVC of the coating composition was determined to be 42.6% (1 g, 30 min,200° C.).

TABLE 4 Ingredient Amount (weight parts) Solvent mixture of dimethylesters of 6.81 C4 to C6 diacids DOWANOL PMA solvent (Dow Chemical) 6.81SOLVESSO 100 solvent (Imperial Oil) 2.27 Resole-type phenoliccrosslinker 15.68 Resole-type phenolic crosslinker 5.00 Aminoformaldehyde crosslinker 0.73 CYCAT 600 acid catalyst solution (20% in0.91 Butylglycol), from Cytec LUBAPRINT 436 wax (L.P. Bader & Co.) 3.18BYK 310 silicone solution (10% in Xylene, 0.41 BYK-Chimie)Polyester-Urethane Polymer of Example 5 58 Xylene 5

The Example 5 coating composition was applied on ETP substrate (2.8/2.8)and coated substrate samples were cured for 10 minutes in a 200° C. ovento obtain cured coatings that had a dry film weight of about 7.9 gramsper square meter. The cured samples were subjected to various tests toassess the properties of the coating. The results of these tests areindicated below in Tables 5A and 5B.

TABLE 5A Number of MEK Double-rubs 50 Wedge Bend 77% Crazing no evidenceEnd Fabrication (non-post lube) OK Porosity (average in milliamps for 6can ends) 8.2 mA

TABLE 5B Porosity (mA) Retort Test Before After Material BlushMicroblistering Adhesion Retort Retort Water 9 10 10 3% Acetic Acid 8 1010 Sulfuration 8 10 10 Simulant NaCl (1%) 9 10 10 8.2 11.1 Each of thesimulant solutions in Table 5B was prepared using deionized water. Avisual assessment was used to determine whether microblisters werepresent in the films. The results were ranked from 0 = very poor, to 10= excellent (or defect-free). The X/Y format of the data corresponds,respectively, to flat/formed areas of the film.

Example 6 Polyester-Urethane Including Norbornene and TricyclodecaneGroups

The polyester-urethane polymer of Example 6 was prepared in a multi-stepsynthesis from the reactants in the indicated amounts in Table 6A below.The oligomer of Component A was synthesized using conventional reactionconditions and methods, with the dicyclopentadiene post-added andreacted with the unsaturation of Component A via a Diels-Alder reactionto incorporate unsaturated bicyclic groups (the DCPD was added over 30minutes and the reaction mixture was held at 160° C. for 5 hours). Theresulting Component A oligomer had an acid value of 0.4, a hydroxylvalue of 109 and was 68.9% solids. The oligomer of Component B wasseparately synthesized using conventional reaction conditions andmethods to yield a semi-solid material having 68.5% solids, an acidvalue of 1.2, and a hydroxyl value of 27. The final resin was formed bycombining Components A and B and the DBTDL, heating the mixture to 90°C., and then adding the IPDI over 30 minutes, flushing withcyclohexanone, and holding the reaction mixture at about 90° C. for 3hours. The resulting polyester-urethane polymer of Example 6 was cutwith organic solvent to yield a resin composition that was 29.1% solidsand had an acid value of 1.2 and a hydroxyl value of 14.5.

TABLE 6A Reactant Percent by weight of polymer solids Component A CHDM31.3 Methyl propane diol 17.7 Terephthalic Acid (TPA) 12.9 IsophthalicAcid (IPA) 25.8 Tin Oxalate 0.1 Maleic Anhydride 7.1 Dicyclopentadiene(DCPD) 5.1 100.0 Component B TCDM 44.2 1,4-Butane Diol 8.2 TerephthalicAcid (TPA) 47.5 Organometallic catalyst 0.1 100.0 Final Resin of Example6 Component A 50.2 Component B 38.8 IPDI 10.9 Dibutyl tin diluarate(DBTDL) 0.1 100.0

The coating composition of Example 6 was prepared by mixing theingredients listed below in Table 6B using a stirrer. The viscosity ofthe resulting coating composition was adjusted with xylene to be in therange of 70 to 80 seconds as measured using a #4 Ford cup at 25° C. Thecoating composition was determined to have a solids content of 38.0%(0.5 grams, 11 min, 204° C.).

TABLE 6B Ingredient Amount (wt-%) Polyester-Urethane of Example 6 73.5Resole-type phenolic crosslinker 15.3 Dibasic Ester (DBE) solvent 7.8Xylene solvent 3.4 100.0

The Example 6 coating composition was applied on ETP substrate (2.8/2.8)and coated substrate samples were cured for 10 minutes at a peak metaltemperature (PMT) of 204° C. to obtain cured coatings that had a dryfilm weight of about 7.8 grams per square meter. The cured samples weresubjected to various tests to assess the properties of the coating. Theresults of these tests are indicated below in Table 6C. The coatingproperties of the cured epoxy-free coating of Example 6 were comparableto a commercial BPA-based epoxy control.

TABLE 6C Dry Adhesion No Failure MEK Double Rubs 35 Impact Craze (26 inlbs/2 lb wt) None 52 mm Can End Fabrication OK Deionoized Water Retort(90′ @ 121° C.) Blush (Liquid/Vapor) None/None Adhesion (Liquid/Vapor)No Failure/No Failure 2% NaCl Retort (90′ @ 121° C.) Blush(Liquid/Vapor) None/None Adhesion (Liquid/Vapor) No Failure/No FailureBlistering (Liquid/Vapor) None/None

The complete disclosure of all patents, patent applications, andpublications, and electronically available material cited herein areincorporated by reference. The foregoing detailed description andexamples have been given for clarity of understanding only. Nounnecessary limitations are to be understood therefrom. The invention isnot limited to the exact details shown and described, for variationsobvious to one skilled in the art will be included within the inventiondefined by the claims. The structural representations depicted hereinare non-limiting with respect to stereochemistry and are intended toencompass all suitable stereoisomers.

1. An article, comprising: a metal substrate of a food or beveragecontainer, or a portion thereof; and a coating applied on at least aportion of a major surface of the substrate, the coating prepared from acoating composition including a polyester polymer having a plurality ofpolycyclic groups, wherein the polymer includes both one or moreunsaturated bicyclic groups and one or more at least tricyclic groups.2. The article of claim 1, wherein a backbone of the polyester polymerincludes both ester and urethane linkages.
 3. The article of claim 1,wherein the one or more unsaturated bicyclic groups are bridged bicyclicgroups and wherein a carbon-carbon double bond is present between atomsof a ring of the unsaturated bicyclic group.
 4. The article of claim 1,wherein the one or more unsaturated bicyclic groups comprisebicyclo[2.1.1]hexene, bicyclo[2.2.1]heptene, bicyclo[2.2.1]heptadiene,bicyclo[2.2.2]octene, bicyclo[2.2.2]octadiene, or a combination thereof.5. The article of claim 1, wherein the one or more unsaturated bicyclicgroups are provided by nadic acid, nadic anhydride, or a mixturethereof.
 6. The article of claim 1, wherein the polycyclic groups arepresent in a backbone of the polymer.
 7. The article of claim 1, whereinthe polymer includes at least 10 weight percent of the polycyclicgroups, based on the weight percent of polycyclic-group-containingmonomer relative to the total weight of the polymer.
 8. The article ofclaim 1, wherein the polymer has a glass transition temperature of atleast 50° C.
 9. The article of claim 1, wherein the polymer has a glasstransition temperature of 80° C. to 125° C.
 10. The article of claim 1,wherein the polymer has an iodine value of at least
 10. 11. The articleof claim 1, wherein the one or more at least tricyclic groups aresaturated groups.
 12. The article of claim 1, wherein the polymerincludes: from 5 to 50 percent by weight of the one or more at leasttricyclic groups, from 1 to 35 percent by weight of the one or moreunsaturated bicyclic groups, wherein the aforementioned weight percentsare based on the amount of at least tricyclic group containing monomerand unsaturated bicyclic group containing monomer incorporated into thepolymer relative to the total weight of the polymer.
 13. The article ofclaim 1, wherein the polymer is derived from ingredients including,based on total weight solids, from 17 to 33 percent by weight oftricyclodecane dimethanol and from 5 to 17 percent by weight of nadicanhydride.
 14. The article of claim 1, wherein the coating composition,based on total weight solids, includes at least 50 weight percent of thepolymer.
 15. The article of claim 1, wherein the polymer furthercomprises one or more polycyclic groups derived from isosorbide,isomannide, isoiodide, or a derivative or combination thereof.
 16. Thearticle of claim 1, wherein the one or more at least tricyclic groupscomprise a substituted or unsubstituted tricyclodecane group.
 17. Thearticle of claim 16, wherein the tricyclodecane group is provided bytricyclodecane dimethanol, tricyclodecane diamine, tricyclodecanediisocyanate, or a derivative or mixture thereof.
 18. A method,comprising: providing a coating composition comprising: a polyesterpolymer having a plurality of polycyclic groups, wherein the polymerincludes one or more unsaturated bicyclic groups and one or more atleast tricyclic groups, and a liquid carrier; and applying the coatingcomposition on a metal substrate prior to, or after, forming the metalsubstrate into a food or beverage can or a portion thereof.
 19. Acoating composition, comprising: at least 10 weight percent, based ontotal solids, of a polyester polymer having: a glass transitiontemperature of at least 50° C., and polycyclic groups that constitute atleast 10 weight percent of the polymer, based on the weight percent ofpolycyclic-group-containing monomer relative to the total weight of thepolymer, wherein the polymer includes both one or more unsaturatedbicyclic groups and one or more at least tricyclic groups; a resolephenolic type crosslinker; and a liquid carrier.
 20. The coatingcomposition of claim 19, wherein a backbone of the polyester polymerincludes urethane linkages.